College of Chemistry, Jilin University, Changchun 130012, PR China.
Key Laboratory for Molecular Enzymology and Engineering of Ministry of Education, Jilin University, Changchun 130023, PR China.
J Photochem Photobiol B. 2017 Sep;174:251-260. doi: 10.1016/j.jphotobiol.2017.08.004. Epub 2017 Aug 5.
Security issues of nanoparticles on biological toxicity and potential environmental risk have attracted more and more attention with the rapid development and wide applications of nanotechnology. In this work, we explored the effect and probable mechanism of nano-TiO on antioxidant activity of copper, zinc superoxide dismutase (Cu, Zn-SOD) under natural light and mixed light at physiological pH. Nano-TiO was prepared by sol-hydrothermal method, and then characterized by X-ray Diffraction (XRD) and Transmission electron micrographs (TEM). The Cu, Zn-SOD was purified by sephadex G75 chromatography and qualitatively analyzed by sodium dodecyl sulfate polypropylene amide gel electrophoresis (SDS-PAGE). The effect and mechanism were elucidated base on Fourier Transform Infrared Spectrometer (FT-IR), Circular Dichroism (CD), zeta potential, and electron spin resonance (ESR) methods. Accompanying the results of FT-IR, CD and zeta potential, it could be concluded that nano-TiO had no effect on the antioxidant activity of Cu, Zn-SOD by comparing the relative activity under natural light at physiological pH. But the relative activity of Cu, Zn-SOD significantly decreased along with the increase of nano-TiO concentration under the mixed light. The results of ESR showed the cause of this phenomenon was the Cu(II) in the active site of Cu, Zn-SOD was reduced to Cu(I) by HO and decreased the content of active Cu, Zn-SOD. The reduction can be inhibited by catalase. Excess O produced by nano-TiO photocatalysis under mixed light accumulated a mass of HO through disproportionation reaction in this experimental condition. The results show that nano-TiO cannot affect the antioxidant activity of Cu, Zn-SOD in daily life. The study on the effect of nano-TiO on Cu, Zn-SOD will provide a valid theory support for biological safety and the toxicological effect mechanism of nanomaterials on enzyme.
随着纳米技术的快速发展和广泛应用，纳米颗粒对生物毒性和潜在环境风险的安全问题越来越受到关注。在这项工作中，我们在生理 pH 值下自然光和混合光下探索了纳米 TiO 对铜锌超氧化物歧化酶 (Cu，Zn-SOD) 抗氧化活性的影响及其可能的机制。纳米 TiO 采用溶胶-水热法制备，并采用 X 射线衍射 (XRD) 和透射电子显微镜 (TEM) 进行了表征。Cu，Zn-SOD 通过 sephadex G75 色谱法进行纯化，并通过十二烷基硫酸钠聚丙烯酰胺凝胶电泳 (SDS-PAGE) 进行定性分析。基于傅里叶变换红外光谱仪 (FT-IR)、圆二色性 (CD)、zeta 电位和电子自旋共振 (ESR) 方法，阐明了作用机制。伴随 FT-IR、CD 和 zeta 电位的结果，可以得出结论，在生理 pH 值下自然光下，纳米 TiO 对 Cu，Zn-SOD 的抗氧化活性没有影响。但是，在混合光下，随着纳米 TiO 浓度的增加，Cu，Zn-SOD 的相对活性显著降低。ESR 的结果表明，这种现象的原因是活性部位的 Cu(II)被 HO 还原为 Cu(I)，从而降低了活性 Cu，Zn-SOD 的含量。该还原可以被过氧化氢酶抑制。在这种实验条件下，纳米 TiO 光催化下产生的过量 O 通过歧化反应在混合光下积累了大量的 HO。结果表明，纳米 TiO 在日常生活中不会影响 Cu，Zn-SOD 的抗氧化活性。研究纳米 TiO 对 Cu，Zn-SOD 的影响将为纳米材料对酶的生物安全性和毒理学作用机制提供有效的理论支持。
